1. Field of the Invention
This invention concerns a moving object detection device, a moving object detection method, and a moving object detection program for detecting, from images taken by cameras, moving objects that exist in the images.
2. Description of Relevant Art
As a prior art of detecting, from an image taken by a CCD or other type of camera, objects that exist in the image, there is for example the art wherein initial ambiguous contours of objects are set as contour models and these contour models are reduced and deformed according to predetermined rules to extract the contours of the objects and thereby detect the objects (active contour model: snakes). In an object detection art based on this contour extraction, the edges of objects with movement (moving objects) are detected from images that are successive in time and the edges are joined to the contour models to extract the contours of moving objects and thereby detect the moving objects (see for example, Patent Literature 1).
Also as an art of separating and extracting individual objects from position (distance) information obtained from a stereo image, etc., there is the art wherein, for example, in a region that is recognized as an object in three-dimensional space, a restricted object position calculation region, in which the object is positioned, is set as an initial region according to the size of the object, the relative position of the object position calculation region with respect to the position of the center of gravity in three-dimensional coordinates of the object is computed, and when this relative position is within a predetermined range with respect to the position of the center of gravity, the position of the center of gravity is specified as the position of the object to thereby extract the object (see for example, Patent Literature 2).
Also as an art of detecting moving objects from images taken by a moving camera, there is the art of analyzing the movement of the moving camera from luminance information in images that are successive in time, this movement is presumed to be the movement of the background, and, based on the differences of the successive images and the movement of the background, the regions of moving objects are detected and extracted as contours (see for example, Non-Patent Literature 1).
[Patent Literature 1]
Japanese Unexamined Patent Publication No. Hei-8-329254 (p. 7, FIG. 9 and FIG. 10).
[Patent Literature 2]
Japanese Unexamined Patent Publication No. Hei-7-49950 (pp. 4 and 5, FIG. 1).
[Non-Patent Literature 1]
Matsuoka, Araki, Yamasawa, Takemura, Yokoya, “Extraction and Tracking of Moving Object Contours from Moving Camera Images and Real-Time Processing by DSP,” The Institute of Electronics, Information and Communication Engineers, Technical Report of The Institute of Electronics, Information and Communication Engineers, PRMU 97–235, 1998.
However, of the above-described prior arts, with the art of the first example, wherein contour models are joined to edges, detected from successive images, to extract the contours of moving objects and thereby detect the objects, in a case where a plurality of objects exist adjacently in the taken images, these plurality of objects are recognized as a single object.
Also, of the above-described prior arts, with the art of the second example in which objects are extracted based on the center-of-gravity positions of the objects, calculations must be performed repeatedly until the relative position of the object position calculation region with respect to the center-of-gravity position falls within the predetermined range and thus the time for object extraction becomes long. This art thus could not be applied to a device, such as a moving robot, that is to perform recognition (extraction) of persons and other objects in real time.
Also, of the above-described prior arts, with the art of the third example in which moving objects are detected by a moving camera, since the entireties of images taken by the moving camera are processed as object regions for contour extraction, the calculation amount becomes large and thus a high-speed processing device is required for successive extraction of the contours of moving objects in real time. Furthermore, as with the above-described first example, in a case where a plurality of objects exist adjacently in the taken images, these plurality of objects are recognized as a single object.
There was thus a need for a moving object detection device, a moving object detection method, and a moving object detection program which enable the calculation processes for performing contour extraction of moving objects to be lightened even with images taken by moving cameras and enable detection of individual objects at high speed even in cases where a plurality of objects exist adjacently in the images taken.